Supermarket Soundtrack

I was walking through the supermarket earlier this evening and I was singing aloud to Ricky Martin...Livin La Vida Loca. I go grocery shopping almost every week, I worked in a supermarket when I was a kid...pretty much from age 15 - 19...and I never stopped to ask the question. Why exactly is it necessary to have a shopping soundtrack? And it's never current music...it's music from the previous decade. It plays for an hour and repeats..."Hold on to the Night"...it's Richard Marx from the 1990s.